Sienna Miller keeps it simple and chic in a silk dress while attending the Rockins Selfridges Pop-Up Shop Launch Celebration held at Park Chinois on Tuesday (July 4) in London, England.

The 35-year-old actress was joined by her pal, Rockins co-founder Jess Morris, and Sienna Guillory at the bash, which included live performances from fashion favorites Wild Daughter, Michael Clark and dancer Harry Alexander.

“We are so proud to be part of Selfridges ‘music matters’ concept,” Jess said in a statement. “Music really does matter – now more than ever. It brings people together and reminds us of the beauty in humanity.”

Sienna was at the festival as well and they hung out in a group that included their mutual friend Bradley Cooper, among others. “They were all hanging out as friends,” a source told Us Weekly. “There’s nothing going on there.”

The source also said that rumors of Brad being involved with Elle are “absolutely not true.”

After his split from Angelina Jolie last year, Brad has been focusing on himself and his kids.

Sienna Miller stopped by The Tonight Show Starring Jimmy Fallon on Wednesday night (April 19) and participated in a hilarious, food-tasting game called Secret Ingredient!

The 35-year-old actress was joined by Jimmy, 42, and special guest, Chef Anthony Bourdain, as they each took turns guessing the unusual secret ingredient hidden in each course of a three-course meal, earning a point if they guess right.

The trio had to guess ingredients like Juicy Fruit gum, Oreo cookie, cheese and hot sauce.

Sienna also sat down on the couch and talked about her current, temporary home in the middle of the woods, and she and Jimmy act out a bit of her latest film The Lost City of Z.

On if her and her ex Tom Sturridge still hang out: “We do bedtime every day. We felt like as much togetherness as possible would be ideal, and fortunately we really love each other and are best friends, and so that works. It’s not that it’s not complicated, because it is.”

On being a single mom: “I had an amazing moment the other day where I just heard this ‘Mama!’ from upstairs,” she says. “I said, ‘I’m coming, I’m coming.’ And as I got to the landing I just smelled, like, puke. And she’d thrown up basically off the top bunk, so the splatters were like: Pow! Like all four walls. She had the norovirus or whatever. I was like, ‘I’m coming, I’m coming!’ And I skidded on the sick and fell. Whacked my head. Then I get her out of the bunk; she’s crying, covered in sick. I take her to the bathroom, take all her clothes off, and then the dog comes up and starts eating the sick. And I get her in the bath and in my bed, and I’m just, like, literally naked, mopping, and crying at midnight. You know, and that’s parenthood. You’re so enriched by it and so fulfilled, but at the same time, I look at these people who just don’t have any responsibility, and it feels like the responsibility is crippling.”

On life after giving birth: “I do miss my breasts being where they were…And, yes, I have nipples like fighter pilots’ thumbs. But I also sort of like that they’re a little ’70s. And that they fed my kid.”